I experienced another hard lock-up last night.
Last time I measured, the board had +5.1 VDC on the test points. The power brick is a dedicated power brick, with a permanent cable going out to a micro-USB connector, and essentially zip-cord (maybe 20-22awg by eye). It is made to power a Raspberry Pi 3.
The only thing I had going on perhaps out of the ordinary, is I had an external computer hitting the API interface once every 10 seconds, and another hitting the filescan point every 10 minutes. I also left an SSH shell connected, but it was just sitting at the command prompt.
I will try letting the DC operate as intended, with no external API calls going into it, and no SSH shells left open.
If it provides a datapoint, when it locks up, there are only two LEDs lit solidly, all the others are dark. I have to hold the power button down for about 5 seconds and it will power off.
If it locks up again I will try re-flashing.